simply to stay indoors. the u.s. and other countries have set a much wider evacuation zone for their people, 80 kilometers or 50 miles from daiichi. >>> now, we've all gotten a crash course in nuclear physics over the past two weeks or so, but to understand the impact of are possible containment breachi want to bring in at. scientist. bill nye, the science guy, joins us live from l.a., and bill knows all about this. bill, good to see you. would a leaking reactor core which we m be seeing here, would it be a major escalation of this disaster or just simply another complication? >> it's probably a major escalation. now, if it's not the core that's cracked, it's some plumbing, some pipes, that lead into it. because when you get this knd of radioactivity level going up so fast, it's probably plutonium. now, this sounds like science fiction, and it kind of is. u transmute uranium into plutonium by giving it a jolt. you change someneutrons into protons and it becomes fantastically radioactive. and glen cyborg himself who won abel prize for creating plutonium, told me it's toxic a